Spin-on filter arrangements have been employed in a variety of applications including, for example, hydraulic systems, fuel systems and lubrication systems. Such filter arrangements generally include a filter element positioned within a can, casing or housing having a cover or top plate at one end thereof, by which the filter can be mounted on a filter head or filter base. A central opening and several surrounding openings in the cover are usually provided to direct flow through the filter and filter element therein, which flow can be in either an inside/out (reverse flow) or an outside/in (forward flow) pattern. A circular gasket on the outside of the cover serves as an external seal between the filter and the filter head. A gasket (or combination of gaskets) on the inside of the cover functions as an internal seal between portions of the filter element and the cover. Spin-on filters are typically intended to be used for a limited period, with follow-up removal and replacement during servicing.
Herein the combination of can, element and other components which are "spun" or otherwise mounted onto the filter base will sometimes be referred to as the removable and replaceable filter cartridge or cartridge assembly.
A variety of conventional arrangements have been used to provide for sealing engagement with respect to fluid flow outwardly from between the filter base and the cartridge. Many of these have concerned positioning an o-ring, compressed, axially, between the two as the filter cartridge is spun onto the filter base. Examples of these are shown: in U.S. Pat. No. 4,969,994, FIG. 1 at 7 and FIG. 3 at 134; in U.S. Pat. No. 4,369,113 in FIG. 2 at 44; and, in U.S. Pat. No. 4,743,374 in FIGS. 2 and 5, at 46. The complete disclosures of the previously mentioned '994, '113 and '374 patents are incorporated herein by reference.
Reliability and durability of the seal between the liquid filter and the filter head is important. Significant leakage of the fluid being filtered during operation can result in catastrophic damage to the engine, vehicle component, or other equipment and component involved.